I suspect you need some 'null' or 'zero' object to handle the case of 'empty folder'.
So ... create a dummy mp3 file, name it as you will, give it tag-fields as you will, ...
and you will stay informed, even from the view of Mp3tag.
There are several ways to create dummy mp3 files, here are some simple proposals ...
Type on the DOS command line ...
ECHO.xxx>dummy.mp3
... or ...
echo.xxx>"%USERPROFILE%\Desktop\dummy.mp3"
... or ...
Execute this Mp3tag export script ...
$filename($getEnv('USERPROFILE')'\Desktop\dummy.mp3',ANSI)'xxx'
... or ...
Use a text editor and save some letters into a file, ...
save it as "dummy.mp3" or what you want.
Load the dummy mp3 into Mp3tag.
DD.20150331.2129.CEST